Microwave phase shifter and method for its manufacture

ABSTRACT

A ferrite phase shifter comprising an elongated bar of ferrite material together with a spirally-wound laminate surrounding the body with successive convolutions of the laminate overlapping preceding convolutions. The laminate comprises a ribbon of insulating material having an outer coating of electrically conductive material thereon whereby a capacitive effect will be produced between successive convolutions. Electromagnetic coil windings can be formed integrally on the outer surface of the ribbon of insulating material whereby, as the laminate is wound onto the ferrite body, a spiral coil is simultaneously formed.

United States Patent [191 McViekers 51 Feb. 4, 1975 [5 1 MICROWAVE'PHA'SE SHIFTER AND METHOD FOR ITS MANUFACTURE [75] Inventor: Jack C. McVickers, Monroeville,

[73] Assignee: Westinghouse Electric Corporation,-

- Pittsburgh, Pa.

22 Filed: Mar. 20, 1974 21 Appl. No.: 452,865

[52] US. Cl 333/31 R, 29/600, 29/605, 333/84 R [51] Int. Cl ..'H03h 7/30, H03h 13/00 [58] Field of Search 333/29, 31 R,.3l A, 31 C, 333/84 R, 94 R, 96, 95 S; 328/109; 29/592, 600-602, 604-606 [56] References Cited UNITED STATES PATENTS 4/1958 Rado 333/95 S 3,735,293 5/1973 Breitenbach 333/84 R Primary Examiner.lames W. Lawrence Assistant Examiner-Marvin Nussbaum Attorney, Agent, or Firm-J. B. l-linson [57] ABSTRACT A ferrite phase shifter comprising an elongated bar of ferrite material together with a spirally-wound laminate surrounding the body with successive convolutions of the laminate overlapping preceding convolutions. The laminate comprises a ribbon of insulating 1 material having an outer coating of electrically conductive material thereon whereby a capacitive effect will be produced between successive convolutions. Electromagnetic coil windings can be formed integrally on the outer surface of the ribbon of insulating material whereby, as the laminate is wound onto the ferrite body, a spiral coil is simultaneously formed.

7 Claims, 3 Drawing Figures PATENTEDFEB 4:915

FIG. 3.

MICROWAVE PHASE SIIIFTER AND METHOD FOR ITS MANUFACTURE BACKGROUND OF THE INVENTION The present invention is particularly adapted for use 5 in applications such as antenna systems employing a plurality of radiating elements which are electronically scanned. That is, by varying the phases of the respective signals fed to the individual radiating elements, the composite radiated beam can be caused to scan back and forth without mechanical movement of the antenna itself.

Such electrically steerable antenna arrays have been made using diode or ferrite phase shifters. In the past, such phase shifters have been formed by evaporating a discontinuous film of conductive material around a ferrite rod. The axial discontinuity in the sleeve of conductive material prohibits the formation of a shorted turn to a surrounding electromagnetic coil. The split in the outer conductor, which extends along the axis of the ferrite rod, is covered with insulating material; and covering the insulating material is a second conductor which forms a capacitive effect with the inner conductive sleeve. This capacitor appears as a short to the high frequency microwave signals while effectively appearing as a non-shorted turn to the lower frequency control signals.

An electronically agile antenna utilizes approximately 5000 ferrite phase shifters of this type. However, because of high labor cost incurred in manufacturing ferrite phase shifters of the-prior art type, their use becomes impractical.

SUMMARY OF THE INVENTION In accordance with the present invention, anew and improved ferrite phase shifter is provided for microwave devices which is amenable to the utilization of high volume, low-cost production techniques. It provides a path for the conductance of the microwave energy along the surfaceofa ferrite rod, which path does not act as a shorted turn secondary of the control coils which encase the ferrite rod.

Specifically, there is provided, in a ferrite phase shifter, the combination of an elongated bar of ferrite material, and a spirally-wound laminate surrounding the body with successive convolutions of the laminate overlapping preceding convolutions. The laminate comprises a ribbon of insulating material having an outer coating of electrically conductive material thereon whereby a capacitive effect will be produced between successive convolutions of the laminate. The laminate may, for example, be formed from a ribbon of MYLAR (Trademark) or some other suitable insulating material having its outer surface metalized to form the electrically conductive coating.

Further, in accordance with the invention, it is possible to form over the outer coating of electrically conductive material strips of MYLAR or some other similar insulating material which have their outer surfaces also metalized, thereby forming thewindings of one or more surrounding electromagnetic coils. Since the laminate is spirally wound, the coil windings formed thereon will also be spirally sound at the same time that the laminate is applied.

The aboveand other objects and features of the invention will become apparent from the'following detailed description taken in connection with the accompanying drawings which form a part of this specification, and in which:

FIG. I is a perspective view of the ferrite phase shifter of the invention;

FIG. 2 is an enlarged view showing the manner in which successive convolutions ofthe laminate of FIG. 1 overlap; and

FIG. 3 is an enlarged view showing the manner in which coil windings can be formed integrally with the ribbon from which the spirally-wound laminate is formed.

I With reference now to the drawings, and particularly to FIG. 1, the phase shifter shown includes a rod 10 of ferrite material surrounded by a spirally-wound laminate 12. The laminate 12 is formed from a continuous ribbon, the pitch of the successive convolutions of the laminate being such that one convolution 12a (FIG. 2) overlaps the next preceding convolution 12b. The continuous ribbon from which the laminate is formed comprises a ribbon of insulating material 16 having a layer 14 of electrically conductive material formed on its inner surface. The layer 14, for example, may be formed by vacuum deposition techniques or any other suitable process.

With the arrangement shown, a capacitive effect is formed between the overlapping convolutions. At the same time, since the electrically conductive material 14 never forms a complete closed loop around the ferrite rod 10, a shorted turn secondary is not presented to surrounding coil windings 18.

The coil windings 18, usually two in number, are provided for producing an electromagnetic field extending axially along the rod 10. The coil windings may be formed, as shown in FIG. 3, integrally with the ribbon which forms the laminate 12. Thus, these can be deposited on the insulating material 16, on the surface opposite the conductive film 14, strips 20 and 22 of a conductive material, thereby forming two electromagnetic coils. These may be connected through leads 26, 28, respectively, to external circuitry designed to control the aforesaid electromagnetic field.

Although the invention has been shown in connection with a certain specific embodiment, it will be readily apparent'to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention.

What is claimed is:

1. In a ferrite phase shifter, the combination of an elongated bar of ferrite material, and a spirally-wound laminate surrounding said body with successive convolutions of the laminate overlapping preceding convolutions, the laminate comprising a ribbon of insulating materialhaving an inner coating of electrically conductive material thereon whereby a capacitive effect will be produced between successive overlapping portions of the convolutions.

2. The ferrite phase-shifter of claim 1 including an electromagnetic coil'surrounding said laminate.

3. The ferrite phase shifter of claim 2 wherein said electromagnetic coil'is formed integrally with said laminate.

4. The ferritephase shifter of claim I wherein said insulating material comprises a plastic having a layer of electrically conductive material deposited on its inner surface.

each other.

7. The method of claim 6 including the step of applying over said ribbon of insulating material a strip of conductive material, whereby said strip of conductive material will form an electromagnetic coil as said ribbon is spirally wrapped around the elongated bar of ferrite material. 

1. In a ferrite phase shifter, the combination of an elongated bar of ferrite material, and a spirally-wound laminate surrounding said body with successive convolutions of the laminate overlapping preceding convolutions, the laminate comprising a ribbon of insulating material having an inner coating of electrically conductive material thereon whereby a capacitive effect will be produced between successive overlapping portions of the convolutions.
 2. The ferrite phase shifter of claim 1 including an electromagnetic coil surrounding said laminate.
 3. The ferrite phase shifter of claim 2 wherein said electromagnetic coil is formed integrally with said laminate.
 4. The ferrite phase shifter of claim 1 wherein said insulating material comprises a plastic having a layer of electrically conductive material deposited on its inner surface.
 5. The ferrite phase shifter of claim 1 wherein said electromagnetic coil comprises a strip of conducting material formed over said insulating material.
 6. In the method for manufacturing a ferrite phase shifter, the step of spirally wrapping around an elongated bar of ferrite material a ribbon of insulating material having a metallic layer on its inner surface, successive convolutions of the spiral wrapping overlying each other.
 7. The method of claim 6 including tHe step of applying over said ribbon of insulating material a strip of conductive material, whereby said strip of conductive material will form an electromagnetic coil as said ribbon is spirally wrapped around the elongated bar of ferrite material. 